PH_RULE_O365_InboxRuleDeleteMessageAction
Enabled
A Mail Inbox Rule was created that specifies the DeleteMessage parameter. This informs O365 to automatically delete matching messages.
9
Security
Collection
Collection consists of techniques adversaries may use to gather information and the sources information is collected from that are relevant to following through on the adversary's objectives. Frequently, the next goal after collecting data is to steal (exfiltrate) the data. Common target sources include various drive types, browsers, audio, video, and email. Common collection methods include capturing screenshots and keyboard input.
https://attack.mitre.org/tactics/TA0009T1114.003
Email Collection: Email Forwarding Rule
Adversaries may setup email forwarding rules to collect sensitive information. Adversaries may abuse email-forwarding rules to monitor the activities of a victim, steal information, and further gain intelligence on the victim or the victim's organization to use as part of further exploits or operations. Any user or administrator within the organization (or adversary with valid credentials) can create rules to automatically forward all received messages to another recipient, forward emails to different locations based on the sender, and more.
https://attack.mitre.org/techniques/T1114/003Application
Office 365 via Management Activity API
Correlation
Investigate that the mail deletion rule was intended by the user who created. It can be a sign of compromise that Mail rules are created to delete messages to hide malicious behavior.
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
o365_mail_rule_delete
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType IN ("MS_OFFICE365_Exchange_New-InboxRule","MS_OFFICE365_Exchange_Set-Mailbox") AND options CONTAIN "DeleteMessage"
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
srcIpAddr,user,ruleName
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 1
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
srcIpAddr=o365_mail_rule_delete.srcIpAddr,
user=o365_mail_rule_delete.user,
ruleName=o365_mail_rule_delete.ruleName